Alkali-refining of fatty glycerides in the presence of a tartaric compound



Patented May 11, 1954 OFFHIE ALKALI-REFINING F FATTY GLYCERIDES IN THE PRESENCE OF A TARTARIC COM- POUND John A. Carlson, Old Tappan, N. J., assignor to Lever Brothers Company, Cambridge, Mass, a

corporation of Maine No Drawing. Application July 19, 1949, Serial No. 105,674

13 Claims. (Cl. 260424) This invention relats to the alkali-refining of fatty'glyceride stocks in the presence of a small amount of a tartaric acid, and especially in one embodiment to the alkali-refining of soybean oil in the presence of a small amount of tartaric acid.

The alkali-refining of fatty glyceride stocks has long been practiced, and extensive information as to procedural details is available in the literature; e. g., Industrial Oil and Fat Products by Alton E. Bailey, Interscience Publishers, Inc., New York, N. Y., 1945, which describes refining processes, among others, that are characterized as the dry method and the wet method. Vegetable Fats and Oils by George S. J amieson, Reinhold Publishing Corporation, New York, 1943, is a further reference.

Generally, alkali-refining involves di-phasic separation of an aqueous phase containing undesirable impurities, and a refined oil phase. The phases may be allowed to separate by ravity, as in kettle refining, or may be separated by centrifugal means. The alkali neutralizes the free fatty acids to form soap, which separates in the aqueous phase along with other impurities. There is usually some saponification of the neutral glycerides and some entrainment of the oil in the soap. The art is confronted with the problem of minimizing these losses of neutral oil, which are a serious economic factor in th large scale refinin processes. This is especially true in batch or kettle refining.

In accordance with the invention, it has been found that the refining losses may be markedly reduced if the alkali-refining is carried out in the presence of a tartaric acid.

This invention is of great commercial significance, inasmuch as it permits alkali-refining in large scale conventional kettles with relatively low losses, e. g., comparable to those obtained by the use of centrifugal equipment, to give a resulting product of satisfactory quality. This permits the use of kettle equipment which is available in many cases. The presence of the tartaric additive also tends to improve the centrifugal refining process, but, of course, the difference is not so marked since the losses in the centrifugal process are relatively lower.

The objects achieved in accordance with the invention include th provision of methods of alkali-refining fatty glyceride stocks with relatively low refining losses; Wherein the refinin is carried out in the presence of a tartaric acid;

the provision of processes of alkali-refining soybean oil in the presence of a small amount of tartaric acid; and other objects which will be apparent as details or embodiments of the invention are set forth hereinafter.

In order to facilitate a clear understanding of the invention, an illustrative embodiment of alkali-refinin soybean oil in the presence of tartaric acid is described. The tartaric acid used is the commercial racemic mixture. Either of the optically active forms of the acid is operative, but such forms would not be used for economic reasons.

The maximum amount of caustic used is calculated from the usual formula form of a 14 B. aqueous solution. In the case of the expeller soybean oils, the maximum amount +0.54 mol of caustic is used in the form of a 12 Be. aqueous solution. Unless otherwise indicated, all amounts and percentages are on an anhydrous weight basis, relative to the amount of oil treated. In the examples immediately following, 0.1 of tartaric acid is used as the additive. It is added to the caustic and then the resulting mixture is immediately added to the oil, at about room temperature, with agitation. Then the temperature of the mixture is raised to about C., with agi tation. Then the mixture is settled. In accordance with the dry method, the refined oil may be removed from the settled foots, e. g., by means of a skim pipe. In accordance with the wet method, the settled mixture may be given a 10% by weight still water wash, and after settling, the aqueous phase removed. The following results are typical when refining by the dry method:

Extracted soybean oil Percent Loss in Refining Example Percent Addltlve No. F. r A.

. Blank 1th Reduc Add. tlon The above reductions in refining losses are noteworthy, especially when the small amount of additive used is considered. The amount of additive may be increased, e. g., following the procedure of Example 6, except using 0.20% of the additive, the same reduction in loss is obtained. In a similar procedure, using 0.5% of the additive, slightly poorer refining losses are obtained than with 0.2%.

The resulting product is of satisfactory quality, and may be bleached with fullers earth or with acid activated clay, and further processed to prepare a shortening.

An embodiment of kettle refining is represented in the above examples, and this is of greatest commercial significance at this time. The excesses of caustic and the concentrations are not critical and may be varied to give a similar efficient result. The tartaric compound may be added to the caustic before it is added to the oil, or added to the oil separately at the same time the caustic is added or later.

The following examples illustrate the use of the additive in a centrifugal refining process. Tartaric acid in an amount of 0.1% is added to 20 1%. caustic and then the latter mixed with degummed extracted soybean oil and agitated at a temperature of 75 F. for 20 minutes before being introduced into the centrifugal machine. The excess caustic was, 0.3%. The following results are typical.

Percent LOss in Refining Exam le Percent No. Addltlve F. 12A. h

Blank i Add. tion 7 Tartaric acid 0.4 1.50 0.70 0.80 8 do 0.4 1.40 0.90 0.50

Percent Loss in Refining Example Percent No. Addmv" F. r. A. Blank With Reduc- Add. tion 9 Tartaric acid. 1.0 6.20 3.78 2. 42 1.0 6.10 3. 80 2. 30 1.0 5.90 3. 84 2.06 1.0 5. 40 4.10 1.30 1. 0 5. 60 3. 74 1. 86

These reductions in refining loss would be reflected in great commercial savings, since cottonseed oil is available in large quantities and the success of the process in refining it is important.

A slow breaking cottonseed oil of 1.1% F. F. A. is refined with 6.3% of 140 B. caustic soda in accordance with the above-described procedure, using 0.1% of tartaric acid. The following results are typical.

Percent Loss in Refining Example Percent Addmve With Reduc- Blank Add. tion 14 Tartaric acid 1.1 6. 36 4. 1. 86 15 "(l0 1.1 6. 36 4.70 1.66

In the case of Example 15, the additive was prepared in the form of a 10% water solution and. then added to the caustic. The method of Example 14 is to be preferred.

Following the usual alkali-refining procedures as applied to known fats and oils (e. g, as described in the literature), especially vegetable oils, refining losses may be reduced substantially by including a small amount of tartaric acid.

In general, the amount of the tartaric acid should be sufi'icient to reduce the refining loss and not so large, etc, as to increase it. An amount of the additive of up to about 0.75% and preferably in the range of 0.02 to about 0.5% by weight calculated as anhydrous, and based on the weight of oil, will generally be suitable. Use of mixtures of the tartaric acids is included in the invention.

Any alkali metal hydroxide may be used as the alkali, but caustic soda is generally used commercially and is preferred.

in view of the foregoing disclosures, variations and modifications thereof will be apparent to those skilled in the art, and the invention contemplates all such variations and modifications except as do not come within the scope of the appended claims.

I claim:

1. In the processes of alkali-refining a d;- gummed fatty glyceride stock by treatment with aqueous alkali and alkali-refining nondegummed fatty glyceride stocks by treatment with aqueous alkali in which at the same time the gums are decomposed by the alkali and dissolved therein, and separating an aqueous phase containing gum residues, if any, and undesirable impurities from a refined oil phase, the improvement which comprises introducing at any stage in the aiizali refining step a small amount up to about 0.75% of a tartaric acid on an anhydrous weight basis relative to the amount of oil treated to reduce the refining losses.

2. The process of claim 1, wherein the phases are separated centrifugally.

3. The process of claim 2 in which the centrifugal separation is carried out in a continuous process.

4. The process of claim 1, wherein the phases are formed into separate layers by settling.

5. The process of claim 4, wherein the aqueous phase is drawn off from below the oil phase.

6. The process of claim 4, wherein the oil phase is drawn off from above the aqueous phase.

7. The process of claim 1, wherein the fatty glyceride is a soybean oil.

8. The process of claim 1, wherein the fatty glyceride is a cottonseed oil.

9. The process of claim 1, wherein the tartaric acid is racemic tartaric acid.

10. The process of claim 1, wherein the tartaric acid is added to the alkali just before the latter is added to the oil.

11. The process of claim 1, wherein the tartaric acid is added in an amount within the range of 0.02% to 0.5%.

12. The process of claim 1, wherein the fatty glyceride treated is soybean oil, the tartaric acid is racemic tartaric acid, the phases are separated by gravity, and the aqueous phase drawn 011 from below the oil phase.

13. The process of claim 1, wherein the fatty 6 glyceride treated is cottonseed oil, the tartaric acid is racemic tartaric acid, the phases are separated by gravity, and the aqueous phase drawn oil from below the oil phase.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 2,242,188 Thurman May 13, 1941 FOREIGN PATENTS Number Country Date 1,484 Great Britain June 15, 1864 

1. IN THE PROCESSES OF ALKALI-REFINING A DEGUMMED FATTY GLYCERIDE STOCK BY TREATMENT WITH AQUEOUS ALKALI AND ALKALI-REFINING NONDEGUMMED FATTY GLYCERIDE STOCKS BY TREATMENT WITH AQUEOUS ALKALI IN WHICH AT THE SAME TIME THE GUMS ARE DECOMPOSED BY THE ALKALI AND DISSOLVED THEREIN, AND SEPARATING AN AQUEOUS PHASE CONTAINING GUM RESIDUES, IF ANY, AND UNDERSIRABLE IMPURITIES FROM A REFINED OIL PHASE, THE IMPROVEMENT WHICH COMPRISES INTRODUCING AT ANY STAGE IN THE ALKALIREFINING STEP A SMALL AMOUNT UP TO ABOUT 0.75% OF A TARTARIC ACID ON AN ANHYDROUS WEIGHT BASIS RELATIVE TO THE AMOUNT OF OIL TREATED TO REDUCEE THE REFINING LOSSES. 